实现对象克隆的两种方式

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实现Cloneable接口并重写Object类中的clone()方法；

/**
 * @author plm
 * @create 2021/3/10 22:43
 */
class Son  implements Cloneable  {
    private String name;
    private int age;

    public Son(String name, int age) {
        this.name = name;
        this.age = age;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    @Override
    public String toString() {
        return "Son{" +
                "name='" + name + '\'' +
                ", age=" + age +
                '}';
    }
}

class People implements Cloneable {
    private String name;
    private int age;
    private Son son;

    public People(String name, int age, Son son) {
        this.name = name;
        this.age = age;
        this.son = son;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public Son getSon() {
        return son;
    }

    public void setSon(Son son) {
        this.son = son;
    }

    @Override
    protected Object clone() throws CloneNotSupportedException {
        return super.clone();
    }

    @Override
    public String toString() {
        return "People{" +
                "name='" + name + '\'' +
                ", age=" + age +
                ", son=" + son +
                '}';
    }
}

public class CloneDemo {
    public static void main(String[] args) {
        People people = new People("张三", 30, new Son("张小三", 2));
        System.out.println("源对象：" + people);
        try {
            People newPeople = (People) people.clone();
            System.out.println("克隆后新对象：" + newPeople);
            System.out.println("======================================尝试修改克隆后新对象的属性====================================");
            newPeople.getSon().setName("李小四");
            newPeople.getSon().setAge(3);
            System.out.println("源对象：" + people);
            System.out.println("克隆后新对象：" + newPeople);
        } catch (CloneNotSupportedException e) {
            e.printStackTrace();
        }
    }
}
/* 输出
源对象：People{name='张三', age=30, son=Son{name='张小三', age=2}}
克隆后新对象：People{name='张三', age=30, son=Son{name='张小三', age=2}}
======================================尝试修改克隆后新对象的属性====================================
源对象：People{name='张三', age=30, son=Son{name='李小四', age=3}}
克隆后新对象：People{name='张三', age=30, son=Son{name='李小四', age=3}}
*/

修改克隆后新对象的属性，源对象的属性也变了——–浅拷贝

实现Serializable接口，通过对象的序列化和反序列化实现克隆；

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;

/**
 * @author plm
 * @create 2021/3/10 22:43
 */
class Son implements Serializable {
    private static final long serialVersionUID = -5713945027627603702L;
    private String name;
    private int age;

    public Son(String name, int age) {
        this.name = name;
        this.age = age;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    @Override
    public String toString() {
        return "Son{" +
                "name='" + name + '\'' +
                ", age=" + age +
                '}';
    }
}

class People implements Serializable {
    private static final long serialVersionUID = -9102017020286042305L;
    private String name;
    private int age;
    private Son son;

    public People(String name, int age, Son son) {
        this.name = name;
        this.age = age;
        this.son = son;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public Son getSon() {
        return son;
    }

    public void setSon(Son son) {
        this.son = son;
    }

    @Override
    public String toString() {
        return "People{" +
                "name='" + name + '\'' +
                ", age=" + age +
                ", son=" + son +
                '}';
    }
}

public class CloneDemo {
    public static void main(String[] args) {
        People people = new People("张三", 30, new Son("张小三", 2));
        System.out.println("源对象：" + people);
        try {
            ByteArrayOutputStream bout = new ByteArrayOutputStream();
            ObjectOutputStream oos = new ObjectOutputStream(bout);
            oos.writeObject(people);
            ByteArrayInputStream bin = new ByteArrayInputStream(bout.toByteArray());
            ObjectInputStream ois = new ObjectInputStream(bin);
            People newPeople = (People) ois.readObject();
            System.out.println("克隆后新对象：" + newPeople);
            System.out.println("======================================尝试修改克隆后新对象的属性====================================");
            newPeople.getSon().setName("李小四");
            newPeople.getSon().setAge(3);
            System.out.println("源对象：" + people);
            System.out.println("克隆后新对象：" + newPeople);
        } catch (IOException | ClassNotFoundException e) {
            e.printStackTrace();
        }
    }
}
/* 输出
源对象：People{name='张三', age=30, son=Son{name='张小三', age=2}}
克隆后新对象：People{name='张三', age=30, son=Son{name='张小三', age=2}}
======================================尝试修改克隆后新对象的属性====================================
源对象：People{name='张三', age=30, son=Son{name='张小三', age=2}}
克隆后新对象：People{name='张三', age=30, son=Son{name='李小四', age=3}}
*/

修改克隆后新对象的属性，源对象的属性不会变——–深度拷贝；
深度拷贝不仅仅拷贝该对象的成员属性，相关联的对象也会一起拷贝；